Over the last number of months, there has been some confusion among dairy farmers as to the value of EBI and the benefits of crossbreeding when making breeding decisions at farm level.

In this article, we review the evidence to assist dairy farmers to make more informed breeding decision this spring.

The value of EBI

The EBI was introduced in 2001 by the ICBF and Teagasc against a backdrop of declining animal and herd fertility performance in the national dairy herd.

Since then, the index has evolved to incorporate 15 traits in total, the most important of which are female fertility, cow survival and milk solids production (kg fat and protein), with these traits having a combined weighting of about 70% of the overall index. So has the EBI delivered at farm level?

Recent work presented at the Teagasc National Dairy Conference compared the performance of 10,470 dairy herds that had herd EBI, female fertility and milk co-op performance data available.

The data was from three sets of ICBF Herdplus reports that had been posted to herd owners in the previous months.

These were the herd EBI report, the herd calving and fertility report and the herd co-op performance report (based on the nine-month period from January to September 2015).

Herds were categorised on the basis of EBI level into 10 evenly spaced categories, such that the top 10% of herds (1,047 herds in total) had an average EBI of €176, the medium 10% category had an EBI of €135 and the bottom 10% of herds had an EBI of €63.

Each level was then evaluated for a number of key performance indicators at farm level, including calving interval (days), six-week calving rate (spring season), percentage of the herd calving as two-year-old heifers (22 to 26 months), litres of milk supplied to the co-op/day, kilogrammes of milk solids supplied to the co-op/day, average milk price (c/l) paid by the co-op and overall milk value/day (derived from litres delivered and milk price).

The results clearly demonstrate the value of EBI across the 10,470 herds, with the high-EBI herds consistently having much better fertility performance and the top 10% of herds approaching target levels with regard to excellent fertility performance.

This is in contrast to the lower-EBI herds, which had much lower levels of herd fertility performance.

Trends in milk performance delivered to the co-op were also very consistent, except for the bottom 10% of herds (in terms of EBI), which had a higher level of milk litres delivered, on the back of higher levels of concentrate feeding (a higher percentage of these herds were liquid milk or split-calving herds).

Subsequent analysis of this dataset has confirmed that the value of EBI was consistent for both spring-calving (about 80% of the herds) and liquid or split-calving systems.

It is important to note that this analysis was across all herds, regardless of breed. So the clear message is that dairy farmers should decide their breed preference and then look to maximise the EBI within that breed.

The value of crossbreeding

Many studies with varying approaches have been conducted by Teagasc Moorepark over the past decade comparing the performance of Jersey crossbred cows with comparable Holstein-Friesian cows.

  • The earliest research was conducted at Ballydague research farm during the period 2006 to 2010. This study included purebreds and crossbred cows. Clear benefits from crossbreeding were observed. The proportion of cows pregnant to first service (+21%), in-calf after six weeks of breeding (+19%) and in-calf after 13 weeks of breeding (+8%) were considerably higher for the Jersey × Holstein-Friesian compared with Holstein-Friesian (and pure Jersey cows). The economic analyses (incorporating differences in cull cow and male calf value) showed that with a fixed land base, the herd of Jersey × Holstein-Friesian cows was 48% more profitable than a herd of either of the parent breeds. The improved profit equated to over €180 per cow per lactation.
  • More recently, crossbred cows have been incorporated into a comparative stocking rate study at Teagasc’s Curtins Research Farm. The EBI value of both the Holstein-Friesian and crossbred cows is similar at just over €200. The study has run for three years. The Jersey crossbred cows are delivering an additional 70kg/ha annually. See more from this study on page 12.
  • At Clonakilty Agricultural College, the trial includes a comparison between Jersey × Holstein-Friesian and straight Holstein-Friesians. The EBI of both groups is again similar (€177 and €175). This study has also run for three years at this point. The Jersey crossbred cows are delivering more milk solids per cow per lactation (457kg v 449kg). They were 10% lighter (-54kg), had 18 percentage units higher pregnancy rate to first service and 10 percentage units higher six-week in-calf rate.
  • The most recent research (Coffey et al), an analysis of 40 commercial dairy herds with data from 2010 to 2012, represents the first evaluation of crossbred and straight-bred cattle within commercial high-EBI dairy herds, and again the results are consistently in line with the research findings from Teagasc research herds: high EBI Jersey × Holstein-Friesian cows produced 25kg milk solids per cow year more than the mean of high EBI purebred Holstein-Friesian and Jersey cattle. Moreover, the crossbred cattle also achieved a 7.5-day shorter calving interval compared with the purebred herd mates within these herds.
  • A similar piece of research conducted by Kelleher et al during development of the “culling” or “cow” index found that crossbred cows had a nine-day shorter calving interval, a 6% greater pregnancy rate in the first six weeks of the breeding season, and a 3% greater survival rate to the next lactation. Lifetime financial heterosis was estimated to be just under €550.
  • This research study at Ballydague also identified an innate advantage by way of intake capacity with the Jersey breed. Jersey cows consumed 4% of bodyweight in grass DM/day. This compared with 3.4% for the Holstein-Friesian and 3.65% for the Jersey crossbred cows. The importance or value of this trait is not appreciated in practice by many at farm level. This trait is critical to the high productivity per unit area achieved with the Jersey and Jersey crossbred cows in the studies outlined above. Detailed anatomical investigations conducted on animals post-slaughter revealed the physiological mechanisms underpinning the differences in intake capacity observed, which tended to be more physical in nature than metabolic. Selection within the Holstein-Friesian breed using EBI will inevitably improve fertility and longevity, but not this unique capability.

    • The research evidence from Moorepark and elsewhere is categorical and consistently shows that high-EBI crossbred dairy cattle outperform high-EBI purebred contemporaries both within research studies and on commercial dairy farms because of lower replacement costs and greater herd productivity. On that basis, dairy herds which combine high-EBI Holstein-Friesian and high-EBI alternative breeds will continue to reap the added benefits of crossbreeding in addition to the benefits of genetic progress in EBI.

    Crossbreeding strategies

    A common question among dairy farmers considering crossbreeding is “where to after the first cross?” Several schemes are available for creating replacement animals via crossbreeding. The three most common are as follows:

    Two-way rotational crossbreeding

    An example is the use of Jersey sires on Holstein-Friesian cows, and this will generate 50% Holstein-Friesian, 50% Jersey F1 offspring with full heterosis. Using Holstein-Friesian sires on these F1 animals will result in a 75% Holstein-Friesian, 25% Jersey backcross animal in the next generation, and half of the original heterosis would be retained. Using Jersey sires in the next generation would lead to 62.5% Jersey, 37.5% Holstein-Friesian offspring, and three-quarters of the original heterosis would be realised. Subsequently, animals will be 67% Holstein, 33% Jersey, or 67% Jersey, 33% Holstein, depending on the generation. Two-thirds of the original (first-cross) heterosis will remain in each subsequent generation.

    Three-way rotational crossbreeding

    The theoretical advantages of a three-breed rotational crossing system are clear but data to recommend it in practice is very limited. The advantage in theory lies in the maximisation of hybrid vigour – 100% in generation two and 87.5% in the longer term. There is a study on three-way crossbreeding under way in Clonakilty, with promising early results.

    Crossbred sires

    Several AI companies are marketing semen from crossbred sires. Typically these sires are recommended for use on the F1 to maintain uniformity in subsequent generations. In practice, the use of crossbred sires increases variability in the resulting progeny, results in a relatively low level of heterosis in later generations (50%) and makes avoidance of inbreeding difficult because it is the popular sire lines from both Jerseys and Holstein-Friesians that prevail. However, some exceptional crossbred sires do exist. This is due to high selection intensity within the New Zealand crossbred population.

    Ensuring progress

    The increasing differential in EBI between the top Holstein-Friesian and the top Jersey sires that currently exists is due to a combination of factors: 1) the success of Ireland’s national breeding programme, the essential ingredient of which has been the incorporation of genomic selection, 2) a lack of an Irish Jersey breeding programme. Based on the research findings presented, Teagasc and ICBF are clear that the productivity/profit gains available via crossbreeding with Jersey are substantial and cannot be disregarded, even taking into account future gains in EBI for the Holstein-Friesians. Teagasc and ICBF have, therefore, embarked on a major joint strategic initiative. This includes:

    1. COW Index. The Cow Own Worth Index has been developed to rank dairy females on expected lifetime profitability, considering total genetic merit (both additive, eg, EBI, and non-additive genetics, eg, heterosis, effects) and environmental or circumstantial effects. In the coming months the COW index will be trialled and refined, ahead of its official launch in the Autumn 2016.

    2. Multi-breed genomics. Research on the potential for genomics in Jerseys under way. Target to have Jersey genomic test proofs by September 2016.

    3. G€N€ IR€LAND. Commitment to review the programme to best promote/encourage the uptake of high EBI JE and JEX test bulls as part of G€N€IR€LAND 2016.

    4. NextGen Jersey Herd. Teagasc to establish a nucleus herd of Elite Jersey females, based on the same principles as the Next Generation Holstein-Friesian herd.

    5. Heterosis. Teagasc and ICBF to continually review and validate best estimates of economic heterosis/benefit of crossbreeding as the breeding programme develops.

    Ultimately, success is dependent on the level of demand for Jersey genetics at commercial farm level. Irish dairy farmers must be willing to embrace the programme by progeny-testing the best young test sires that will emerge. This is a fundamental step in facilitating the realisation of high-EBI jersey sires to further advance genetic progress within crossbred dairy herds.

    Concluding comment

    Notwithstanding the substantial progress that has been achieved within the Irish dairy herd since the introduction of EBI, national statistics reveal that there is considerable scope for improvement in both productivity and reproductive performance.

    The research evidence clearly shows that high-EBI crossbred cattle outperform purebreds across a vast array of performance parameters. The additional benefit from Jersey crossbreeding is estimated to be valued at up to €150 per lactation.

    The challenge for Teagasc and ICBF is to deliver a Jersey breeding programme that will enable Irish dairy farmers to capitalise on the additional performance and profit crossbreeding with high EBI Jersey can offer.

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    To read the full Spring Al Focus Supplement click here.